A 16 Mev/Nucleon Cocktail for Heavy Ion Testing (open access)

A 16 Mev/Nucleon Cocktail for Heavy Ion Testing

This report gives the description of a new cocktail of heavy ions ranging from Z=7-36 at 16 MeV/Nucleon.
Date: July 31, 2004
Creator: McMahan, M. A.; Leitner, D.; Gimpel, T.; Morel, J.; Ninemire, B.; Siero, R. et al.
System: The UNT Digital Library
Untangling CP violation and the mass hierarchy in long baseline experiments (open access)

Untangling CP violation and the mass hierarchy in long baseline experiments

None
Date: July 31, 2004
Creator: Mena, Olga; Parke, Stephen J. & Fermilab
System: The UNT Digital Library
Large Area Imaging Detector for Long-Range, Passive Detection Of Fissile Material (open access)

Large Area Imaging Detector for Long-Range, Passive Detection Of Fissile Material

Recent events highlight the increased risk of a terrorist attack using either a nuclear or a radiological weapon. One of the key needs to counter such a threat is long-range detection of nuclear material. Theoretically, gamma-ray emissions from such material should allow passive detection to distances greater than 100 m. However, detection at this range has long been thought impractical due to fluctuating levels of natural background radiation. These fluctuations are the major source of uncertainty in detection and mean that sensitivity cannot be increased simply by increasing detector size. Recent work has shown that this problem can be overcome through the use of imaging techniques. In this paper we describe the background problems, the advantages of imaging and the construction of a prototype, large-area (0.57 m{sup 2}) gamma-ray imager to detect nuclear materials at distances of {approx}100 m.
Date: July 30, 2004
Creator: Ziock, K P; Craig, W W; Fabris, L; Lanza, R C; Gallagher, S; Horn, B P et al.
System: The UNT Digital Library
NIC-based Reduction Algorithms for Large-scale Clusters (open access)

NIC-based Reduction Algorithms for Large-scale Clusters

Efficient algorithms for reduction operations across a group of processes are crucial for good performance in many large-scale, parallel scientific applications. While previous algorithms limit processing to the host CPU, we utilize the programmable processors and local memory available on modern cluster network interface cards (NICs) to explore a new dimension in the design of reduction algorithms. In this paper, we present the benefits and challenges, design issues and solutions, analytical models, and experimental evaluations of a family of NIC-based reduction algorithms. Performance and scalability evaluations were conducted on the ASCI Linux Cluster (ALC), a 960-node, 1920-processor machine at Lawrence Livermore National Laboratory, which uses the Quadrics QsNet interconnect. We find NIC-based reductions on modern interconnects to be more efficient than host-based implementations in both scalability and consistency. In particular, at large-scale--1812 processes--NIC-based reductions of small integer and floating-point arrays provided respective speedups of 121% and 39% over the host-based, production-level MPI implementation.
Date: July 30, 2004
Creator: Petrini, F.; Moody, A. T.; Fernandez, J.; Frachtenberg, E. & Panda, D. K.
System: The UNT Digital Library
Random Growth of Interfaces as a Subordinated Process (open access)

Random Growth of Interfaces as a Subordinated Process

Article discussing the random growth of interfaces as a subordinated process.
Date: July 30, 2004
Creator: Failla, Roberto; Grigolini, Paolo; Ignaccolo, Massimiliano & Schwettmann, Arne
System: The UNT Digital Library
Twisted Split Fermions (open access)

Twisted Split Fermions

The observed flavor structure of the standard model arises naturally in ''split fermion'' models which localize fermions at different places in an extra dimension. It has, until now, been assumed that the bulk masses for such fermions can be chosen to be flavor diagonal simultaneously at every point in the extra dimension, with all the flavor violation coming from the Yukawa couplings to the Higgs. We consider the more natural possibility in which the bulk masses cannot be simultaneously diagonalized, that is, that they are twisted in flavor space. We show that, in general, this does not disturb the natural generation of hierarchies in the flavor parameters. Moreover, it is conceivable that all the flavor mixing and CP-violation in the standard model may come only from twisting, with the five-dimensional Yukawa couplings taken to be universal.
Date: July 30, 2004
Creator: Grossman, Yuval; Harnik, Roni; Perez, Gilad; Schwartz, MatthewD. & Surujon, Ze'ev
System: The UNT Digital Library
Cluster Form Factor Calculation in the Ab Initio No-Core Shell Model (open access)

Cluster Form Factor Calculation in the Ab Initio No-Core Shell Model

None
Date: July 29, 2004
Creator: Navratil, P
System: The UNT Digital Library
Considerations for Efficient Airflow Design in Cleanrooms (open access)

Considerations for Efficient Airflow Design in Cleanrooms

A high-performance cleanroom should provide efficient energy performance in addition to effective contamination control. Energy-efficient designs can yield capital and operational cost savings, and can be part of a strategy to improve productivity in the cleanroom industry. Based upon in-situ measurement data from ISO Class 5 clean rooms, this article discusses key factors affecting cleanroom air system performance and benefits of efficient airflow design in clean rooms. Cleanroom HVAC systems used in the semiconductor, pharmaceutical, and healthcare industries are very energy intensive, requiring large volumes of cleaned air to remove or dilute contaminants for satisfactory operations. There is a tendency, however, to design excessive airflow rates into cleanroom HVAC systems, due to factors such as design conservatism, lack of thorough understanding of airflow requirements, concerns about cleanliness reliability, and potential design and operational liabilities. Energy use of cleanroom environmental systems varies with system type and design, cleanroom functions, and the control of critical parameters such as temperature and humidity. In particular, cleanroom cleanliness requirements specified by cleanliness class have an impact on overall energy use. A previous study covering Europe and the US reveals annual cleanroom electricity usage for cooling and fan energy varies significantly depending on cleanliness class, and …
Date: July 29, 2004
Creator: Xu, Tengfang
System: The UNT Digital Library
A Generalized Mass Lumping Technique for Vector Finite Element Solutions of the Time Dependent Maxwell Equations (open access)

A Generalized Mass Lumping Technique for Vector Finite Element Solutions of the Time Dependent Maxwell Equations

None
Date: July 29, 2004
Creator: Fisher, A; Rieben, R; Rodrigue, G & White, D
System: The UNT Digital Library
High Level Waste Tank Closure Modeling with Geographic Information Systems (GIS) (open access)

High Level Waste Tank Closure Modeling with Geographic Information Systems (GIS)

Waste removal from 49 underground storage tanks located in two tank farms involves three steps: bulk waste removal, water washing to remove residual waste, and in some cases chemical cleaning to remove additional residual waste. Not all waste can be completely removed by these processes-resulting in some residual waste loading following cleaning. Completely removing this residual waste would be prohibitively expensive; therefore, it will be stabilized by filling the tanks with grout. Acceptable residual waste loading inventories were determined using one-dimensional groundwater transport modeling to predict future human exposure based on several scenarios. These modeling results have been incorporated into a geographic information systems (GIS) application for rapid evaluation of various tank closure options.
Date: July 29, 2004
Creator: BOLLINGER, JAMES
System: The UNT Digital Library
Lattice disorder and magnetism in f-electron intermetallics (open access)

Lattice disorder and magnetism in f-electron intermetallics

Real materials can have real differences compared to ideal systems. For instance, non-Fermi liquid (NFL) behavior was initially thought to be due to chemical disorder, since the first such materials were all substituted. Although several nominally well-ordered NFL's have been discovered and extensively studied, the effect of disorder on the magnetic properties of f-electron intermetallic systems remains poorly understood. Disorder in NFL systems is reviewed from an experimental, local structure point of view, including a discussion of results on the nominally ordered U{sub 3}Ni{sub 3}Sn{sub 4} and CeCoIn{sub 5} systems, and the chemically disordered UCu{sub 4}Pd and CeRhRuSi{sub 2} systems.
Date: July 29, 2004
Creator: Booth, C.H.; Han, S.-W.; Skanthakumar, S. & Sarrao, J.L.
System: The UNT Digital Library
Multi-Pulse Effects in the Damage to the LCLS Reflective Optics (open access)

Multi-Pulse Effects in the Damage to the LCLS Reflective Optics

A number of experiments to be performed on the planned Linac Coherent Light Source (LCLS) will have to use various types of reflective optics (see, e.g., [1]). On the other hand, LCLS will operate at a rate of 120 x-ray pulses per second. Therefore, when considering effects leading to the damage to its optics, one has to be concerned not only with a possible damage within one pulse, but also with effects accumulating during many pulses. We identify and analyze two of such effects: a thermal fatigue, and the intensity-dependent radiation damage. The first effect is associated with thermal stresses and deformations that occur in every pulse. The heating of the surface layers of the optics leads to a peculiar distribution of stresses, with a strong concentration near the surface. The quasistatic analysis of this problem was presented in [2]. In the present study, we show that transients in both transverse and longitudinal acoustic perturbations play a significant role and generally worsen the situation. If the maximum stresses approach the yield strength, the thermal fatigue causes degradation of the surface within a few thousands pulses. The second effect is related to formation of clusters of ionized atoms which lead to …
Date: July 29, 2004
Creator: Ryutov, D
System: The UNT Digital Library
Optical Pumping Experiments on Next Generation Light Sources (open access)

Optical Pumping Experiments on Next Generation Light Sources

Laser-based plasma spectroscopic techniques have been used with great success to determine the line shapes of atomic transitions in plasmas, study the population kinetics of atomic systems embedded in plasmas, and look at the redistribution of radiation. However, the possibilities for optical lasers end for plasmas with n{sub e}>10{sup 22}cm{sup -3} as light propagation is severely altered by the plasma. The construction of the Tesla Test Facility(TTF) at DESY(Deutsche Elektronen-Synchrotron), a short pulse tunable free electron laser in the vacuum-ultraviolet and soft X-ray regime (VUV FEL), based on the SASE(self amplified spontaneous emission) process, will provide a major advance in the capability for dense plasma-related research. This source will provide 10{sup 13} photons in a 200 fs duration pulse that is tunable from {approx} 6nm to 100nm. Since an VUV FEL will not have the limitation associated with optical lasers the entire field of high density plasmas kinetics in laser produced plasma will then be available to study with tunable source. Thus, one will be able to use this and other FEL x-ray sources to pump individual transitions creating enhanced population in the excited states that can easily be monitored. We show two case studies illuminating different aspects of plasma …
Date: July 29, 2004
Creator: Moon, S J; Fournier, K B; Scott, H; Chung, H K & Lee, R W
System: The UNT Digital Library
Shock Compressing Diamond to a Conducting Fluid (open access)

Shock Compressing Diamond to a Conducting Fluid

Laser generated shock reflectance data show that diamond undergoes a continuous transition from optically absorbing to reflecting between Hugoniot pressures 600<P{sub H}<1000 GPa. The data are consistent with diamond having a thermal population of carriers at P{sub H}{approx}600 GPa, undergoing band overlap metallization at P{sub H}{approx}1000 GPa and melting at 800<P{sub H}<1000 GPa. The results agree well with an equation of state model that predicts that elemental carbon remains solid throughout the interior of Neptune.
Date: July 29, 2004
Creator: Bradley, D K; Eggert, J H; Hicks, D G; Celliers, P M; Moon, S J; Cauble, R C et al.
System: The UNT Digital Library
Thermophotovoltaic Array Optimization (open access)

Thermophotovoltaic Array Optimization

A systematic approach to thermophotovoltaic (TPV) array design and fabrication was used to optimize the performance of a 192-cell TPV array. The systematic approach began with cell selection criteria that ranked cells and then matched cell characteristics to maximize power output. Following cell selection, optimization continued with an array packaging design and fabrication techniques that introduced negligible electrical interconnect resistance and minimal parasitic losses while maintaining original cell electrical performance. This paper describes the cell selection and packaging aspects of array optimization as applied to fabrication of a 192-cell array.
Date: July 29, 2004
Creator: SBurger; Brown, E; Rahner, K; Danielson, L; Openlander, J; Vell, J et al.
System: The UNT Digital Library
Absorption and Emission in the Non-Poissonian Case (open access)

Absorption and Emission in the Non-Poissonian Case

Article on absorption and emission in the Non-Poissonian Case.
Date: July 28, 2004
Creator: Aquino, Gerardo; Palatella, Luigi & Grigolini, Paolo
System: The UNT Digital Library
Dispersion of waves in porous cylinders with patchy saturation Part I. Formulaton and torsional waves (open access)

Dispersion of waves in porous cylinders with patchy saturation Part I. Formulaton and torsional waves

Laboratory experiments on wave propagation through saturated and partially saturated porous media have often been conducted on porous cylinders that were initially fully saturated and then allowed to dry while continuing to acquire data on the wave behavior. Since it is known that drying typically progresses from outside to inside, a sensible physical model of this process is concentric cylinders having different saturation levels--the simplest example being a fully dry outer cylindrical shell together with a fully wet inner cylinder. We use this model to formulate the equations for wave dispersion in porous cylinders for patchy saturation (i.e. drainage) conditions. In addition to multiple modes of propagation obtained numerically from these dispersion relations, we find two distinct analytical expressions for torsional wave modes. We solve the dispersion relation for torsional waves for two examples: Massillon sandstone and Sierra White granite. The drainage analysis appears to give improved agreement with the data for both these materials.
Date: July 28, 2004
Creator: Berryman, J G & Pride, S R
System: The UNT Digital Library
Effect of Sodium Sulfide on Ni-Containing Carbon Monoxide Dehydrogenases (open access)

Effect of Sodium Sulfide on Ni-Containing Carbon Monoxide Dehydrogenases

OAK-B135 The structure of the active-site C-cluster in CO dehydrogenase from Carboxythermus hydrogenoformans includes a {mu}{sup 2}-sulfide ion bridged to the Ni and unique Fe, while the same cluster in enzymes from Rhodospirillum rubrum (CODH{sub Rr}) and Moorella thermoacetica (CODH{sub Mt}) lack this ion. This difference was investigated by exploring the effects of sodium sulfide on activity and spectral properties. Sulfide partially inhibited the CO oxidation activity of CODH{sub Rr} and generated a lag prior to steady-state. CODH{sub Mt} was inhibited similarly but without a lag. Adding sulfide to CODH{sub Mt} in the C{sub red1} state caused the g{sub av} = 1.82 EPR signal to decline and new features to appear, including one with g = 1.95, 1.85 and (1.70 or 1.62). Removing sulfide caused the g{sub av} = 1.82 signal to reappear and activity to recover. Sulfide did not affect the g{sub av} = 1.86 signal from the C{sub red2} state. A model was developed in which sulfide binds reversibly to C{sub red1}, inhibiting catalysis. Reducing this adduct causes sulfide to dissociate, C{sub red2} to develop, and activity to recover. Using this model, apparent K{sub I} values are 40 {+-} 10 nM for CODH{sub Rr} and 60 {+-} 30 …
Date: July 28, 2004
Creator: Feng, Jian & Lindahl, Paul A.
System: The UNT Digital Library
Effects of Model Resolution and Subgrid-Scale Physics on the Simulation of Daily Precipitation in the Continental United States (open access)

Effects of Model Resolution and Subgrid-Scale Physics on the Simulation of Daily Precipitation in the Continental United States

We analyze simulations of the global climate performed at a range of spatial resolutions to assess the effects of horizontal spatial resolution on the ability to simulate precipitation in the continental United States. The model investigated is the CCM3 general circulation model. We also preliminarily assess the effect of replacing cloud and convective parameterizations in a coarse-resolution (T42) model with an embedded cloud-system resolving model (CSRM). We examine both spatial patterns of seasonal-mean precipitation and daily-timescale temporal variability of precipitation in the continental United States. For DJF and SON, high-resolution simulations produce spatial patterns of seasonal-mean precipitation that agree more closely with observed precipitation patterns than do results from the same model (CCM3) at coarse resolution. However, in JJA and MAM, there is little improvement in spatial patterns of seasonal-mean precipitation with increasing resolution, particularly in the Southeast. This is owed to the dominance of convective (i.e., parameterized) precipitation in these two seasons. We further find that higher-resolution simulations have more realistic daily precipitation statistics. In particular, the well-known tendency at coarse resolution to have too many days with weak precipitation and not enough intense precipitation is partially eliminated in higher-resolution simulations. However, even at the highest resolution examined here …
Date: July 28, 2004
Creator: Duffy, P. B.; Iorio, J. P.; Govindasamy, B.; Thompson, S. L.; Khairoutdinov, M. & Randall, D.
System: The UNT Digital Library
Enhancing Facility Operations through Electronic Procedures (open access)

Enhancing Facility Operations through Electronic Procedures

Design of integrated solutions fusing existing facility practices with emerging technology is creating new platforms for enhancing operations. Review of current business methods uncovered several areas of improvement including; operating efficiency, document routing, accountability, reporting, records management, format standardization, and control system interaction. A new Defense Programs (DP) facility at the Savannah River Site (SRS) is implementing an electronic procedure environment to overcome these challenges. Electronic procedures merge disciplines of design engineering, procedure writing, controls engineering, and operations into a central development platform for creating optimal plant processes. Users develop procedures through a combination of logical flowcharts, customizable properties, and Distributed Control System (DCS) functions resulting in the generation of static and dynamic operating procedures, software documentation, and automation code. Execution of developed procedures occurs in a single, uniform, procedure-oriented interface designed specifically for the operator in order to reduce process mistakes, present online information, list approved procedures, organize systems, launch audible alerts, and strengthen communications with automation. Creation of executed documents upon procedure completion and custom reports containing detailed shift turnover information are additional managerial benefits incorporated into the interface. Initial and continuing application improvements from an evaluation of developer feedback, process configurations, and facility integration are reviewed. Incorporation …
Date: July 28, 2004
Creator: TEMPLES, JOE
System: The UNT Digital Library
Managing discovery risks--A Tevatron case study (open access)

Managing discovery risks--A Tevatron case study

To meet the increasing need for higher performance, Management of Fermi National Accelerator Laboratory has undertaken various projects to improve systems associated with the Tevatron high-energy particle collider located at Batavia, Illinois. One of the larger projects is the Tevatron Beam Position Monitor (BPM) system. The objective of this project is to replace the existing BPM electronics and software system that was originally installed during early 1980s, along with the original construction of the Tevatron.The original system consists of 236 beam position monitors located around the underground tunnel of the accelerator. Above ground control systems are attached to these monitors using pickup cables. When the Tevatron collider is operational, signals received from the BPMs are used to perform a number of control and diagnostic tasks. The original system can only capture the proton signals from the collider. The new system, when fully operational, will be able to capture combined proton and antiproton signals and will be able to separate the antiproton signal from the combined signal at high resolution. This significant enhancement was beyond the range of technical capabilities when the Tevatron was constructed about two decades ago. To take advantage of exceptional progress made in the hardware and software …
Date: July 28, 2004
Creator: Banerjee, Bakul
System: The UNT Digital Library
Monolithic Nanocrystalline Au Fabricated by the Compaction of Nanoscale Foam (open access)

Monolithic Nanocrystalline Au Fabricated by the Compaction of Nanoscale Foam

We describe a two-step dealloying/compaction process to produce nanocrystalline Au. First, nanocrystalline/nanoporous Au foam is synthesized by electrochemically-driven dealloying. The resulting Au foams exhibit porosities of 60 and 70% with pore sizes of {approx} 40 and 100 nm, respectively, and a typical grain size of <50 nm. Second, the nanoporous foams are fully compacted to produce nanocrystalline monolithic Au. The compacted Au was characterized by TEM and X-ray diffraction and tested by depth-sensing nanoindentation. The compacted nanocrystalline Au exhibits an average grain size of <50 nm and hardness values ranging from 1.4 to 2.0 GPa, which are up to 4.5 times higher than the hardness values obtained from polycrystalline Au.
Date: July 28, 2004
Creator: Hodge, A. M.; Biener, J.; Hsiung, L. M.; Hamza, A. V. & Satcher, J. H.
System: The UNT Digital Library
Oxygen monitoring cells at Fermilab (open access)

Oxygen monitoring cells at Fermilab

Questions have been raised about the accuracy of oxygen monitoring for personnel safety around systems containing gases with a molecular weight less than nitrogen. A study has been performed to test the accuracy of the oxygen monitoring devices used at Fermilab. Portable and fixed oxygen monitoring equipment is used throughout Fermilab for personnel safety in defined oxygen deficiency hazard (ODH) areas. The results are presented as well as corrective measures taken to ensure accuracy and maintain the proper level of personnel safety.
Date: July 28, 2004
Creator: Theilacker, Jay C.
System: The UNT Digital Library
Physics at an upgraded proton driver at Fermilab (open access)

Physics at an upgraded proton driver at Fermilab

The accelerator-based particle physics program in the US is entering a period of transition. This is particularly true at Fermilab which for more than two decades has been the home of the Tevatron Proton-Antiproton Collider, the World's highest energy hadron collider. In a few years time the energy frontier will move to the LHC at CERN. Hence, if an accelerator-based program is to survive at Fermilab, it must evolve. Fermilab is fortunate in that, in addition to hosting the Tevatron Collider, the laboratory also hosts the US accelerator-based neutrino program. The recent discovery that neutrino flavors oscillate has opened a new exciting world for us to explore, and has created an opportunity for the Fermilab accelerator complex to continue to address the cutting-edge questions of particle physics beyond the Tevatron Collider era. The presently foreseen neutrino oscillation experiments at Fermilab (MiniBooNE [1] and MINOS [2]) will enable the laboratory to begin contributing to the Global oscillation physics program in the near future, and will help us better understand the basic parameters describing the oscillations. However, this is only a first step. To be able to pin down all of the oscillation parameters, and hopefully make new discoveries along the way, …
Date: July 28, 2004
Creator: Geer, Steve
System: The UNT Digital Library